We are studying neural mechanisms that relate to and account for auditory sensation and behavior. Our basic interest is in how the auditory system is organized to measure and encode cues relevant to certain aspects of sound sation, especially sound localization and pitch. Organizational principles can be revealed through experiments that relate the responses of single neurons stimulated with simple acoustic stimuli (e.g., tones of different frequency; tones or band-limited noises in different locations in space) to their locations within auditory nuclei. The products of such experiments are functional maps that reveal how the spatial organization of nuclei and cortical fields under study can account for their known functional (behavioral) results. Organizational principles can also be revealed in anatomical-physiological studies of the projections from level to level in the system. These studies reveal how the response properties of neurons at each level arise as a product of highly-ordered, invariably convergent projections into that level. These HRP, TAA and 2-DG tracer experiments, combined with physiological studies, also reveal how very different information about sound abstracted by a large number of projecting brainstem auditory nuclei is processed within higher auditory nuclei and cortical fields. Studies conducted in somatosensory cortex have revealed a remarkable reorganization of cortex follows restricted peripheral deafferentation. Studies are directed toward determining the functional significance, on several levels, of this cortical "plasticity". These results shall be related to known psychoacoustic behavior, and should provide basic information about how the auditory nervous system is organized to generate these sensational phenomena.